MANUAL AQUIFER TESTING METHODS FOR GROUNDWATER SUPPLY DEVELOPMENT

Effective groundwater supply planning and watershed management plans should be based on usage data and water availability (defined by regional aquifer properties and well capacities), but such information is often lacking in rural areas of the developing world. Simple and economical manual pumping test methods would be valuable for institutions working in community water supply and groundwater management. Towards this end, two types of manual pumping tests were tested to estimate aquifer properties important for modeling and management purposes. One type was performed with existing rope-pump infrastructure in small-diameter drilled wells in fractured bedrock aquifers in Nicaragua, and the other using a manual bailer test in large-diameter dug wells in unconsolidated aquifers in Mali. Replicate field-testing and a high-rate validation test of the rope-pump manual test method were performed, and data from different phases of the tests were analyzed using methods that ranged from a simple spreadsheet approach for ideal conditions and to advanced software for matching analytical solutions to non-ideal conditions. A computer model was used to identify the most reliable and accurate data analysis methods for circumstances in which computer support and technical expertise are limited. These tests were performed to derive information supporting various management purposes. In Nicaragua, a series of manual pumping tests conducted in specific wells on a monthly basis over the course of an entire year quantified seasonal changes in well productivities. In another area of Nicaragua, the manual pumping test method was employed to investigate relationships between well productivity and proximity to fracture/fault zones in volcanic terrains. In Mali, results of the bailer pumping tests, along with a watershed-scale water balance, provided parameter estimates for aquifer modeling that was used to explore well-field configuration options for community water supply development.